[nicoburns]

There's an accessibility setting which you can use to further darken the screen. I have it set to toggle on a triple click of the home button.

[lbotos]

Reduce Whitepoint? Seems to have that effect but not sure if that's the one you are thinking.

[jseutter]

I think they're talking about the accesibility filters: https://9to5mac.com/2016/03/18/how-to-reduce-iphone-screen-b...

I used to use it daily just before going to sleep, but then found the app I read with has a white text on black background that I prefer. Using both at the same time makes it too dark for my eyes, which is a good problem to have.